The present invention relates to a thermal ink transfer printing material and, more particularly, to a thermal ink transfer printing material having a heat-melting or heat-sublimating transferring ink layer on one surface thereof and an anti-sticking layer on the other surface thereof.
With the recently increasing demand for information, various kinds of recording system have been developed and put to practical use. Above all, a thermal ink transfer printing system has become widespread since it has various advantages that the printing operation produces little noise, the apparatus is comparatively cheap and it has a light weight and excellent in operability and maintenance property, printing is possible on ordinary paper, and the printed record withstands a long-time storage.
In this system, a thermal ink transfer printing material comprising a base film provided with a heat-melting or heat-sublimating ink layer on one surface thereof is conventionally used. As the base film of a conventional thermal ink transfer printing material, a plastic film such as polyester film, polypropylene film, polyimide film and aromatic polyamide film, and condenser paper each having a thickness of 2 to 20 .mu.m is used. Among these, a polyester film is generally used because it is excellent in thickness uniformity surface smoothness and the operability in a printer, and it is comparatively cheap.
A thermal ink transfer printing material using a polyester film as the base film, however, sometimes produces what is called a sticking phenomenon. In other words, the surface temperature of a thermal head rises above the melting point of the base film during printing, and the film which comes into contact with the thermal head is fused to the thermal head, thereby hindering the feeding of the thermal ink transfer printing material. The solution of this problem has become very important due to the increase in the energy applied to the thermal head with the recent development of high-speed printing and high-density printing, and due to multi-color printing.
As a solution to this problem, a method is proposed of providing a thermoplastic resin layer or a thermosetting resin layer as an anti-sticking layer, which contains a lubricant such as a surfactant and silicone oil, on the surface of the base film which comes into contact with a thermal head. Formation of such an anti-sticking layer, however, produces other problems. For example, the lubricant bleeds out to the surface of the anti-sticking layer and, as a result, dust adheres to the surface of the film, which leads to the contamination of the thermal head or misprint, or when the thermal ink transfer printing material is rolled up, the lubricant transfers to the other side of the base film and lowers the adhesion between the base film and the transfer ink layer or the adhesion between the recording paper and the transfer ink. In addition, the adhesion between the base film and the anti-sticking layer is insufficient,and the anti-sticking layer is sometimes peeled off, which leads to the contamination of the thermal head or misprint.